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architecture Behavioral of serial_receiver is
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architecture Behavioral of serial_receiver is
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signal current_s: rxStates;
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signal current_s: rxStates;
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signal filterRx : rxFilterStates;
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signal filterRx : rxFilterStates;
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signal syncDetected : std_logic;
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signal syncDetected : std_logic;
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--signal getPoint : std_logic;
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begin
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begin
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-- First we need to oversample(4x baud rate) out serial channel to syncronize with the PC
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-- First we need to oversample(4x baud rate) out serial channel to syncronize with the PC
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process (rst, baudOverSampleClk, serial_in, current_s)
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process (rst, baudOverSampleClk, serial_in, current_s)
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begin
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begin
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else
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else
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filterRx <= s0;
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filterRx <= s0;
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end if;
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end if;
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when s3 =>
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when s3 =>
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syncDetected <= '0';
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if serial_in = '0' then
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filterRx <= s4;
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syncDetected <= '0';
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else
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filterRx <= s0;
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end if;
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when s4 =>
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-- Real Beginning of start bit detected
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-- Real Beginning of start bit detected
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if serial_in = '0' then
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if serial_in = '0' then
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filterRx <= s3;
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filterRx <= s4;
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syncDetected <= '1';
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syncDetected <= '1';
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end if;
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end if;
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-- Reset out sync detector when finished to receive a byte
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-- Reset out sync detector when finished to receive a byte
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if current_s = rx_idle then
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if current_s = rx_idle then
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end if;
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end if;
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end process;
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end process;
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-- Process to handle the serial receive (On this case our reset is the syncDetected signal
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-- Process to handle the serial receive (On this case our reset is the syncDetected signal
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-- Always include all of your signals on the sensivity list!! (Even if the simulation is already ok)
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-- Always include all of your signals on the sensivity list!! (Even if the simulation is already ok)
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process (syncDetected, baudClk, serial_in)
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process (syncDetected, baudOverSampleClk, serial_in)
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variable byteReceived : STD_LOGIC_VECTOR ((nBits-1) downto 0);
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variable byteReceived : STD_LOGIC_VECTOR ((nBits-1) downto 0);
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variable waitBestPoint : integer range 0 to 10;
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constant numTicks : integer := 7;
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begin
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begin
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if syncDetected = '0' then
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if syncDetected = '0' then
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current_s <= bit0;
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current_s <= bit0;
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data_ready <= '0';
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data_ready <= '0';
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byteReceived := (others => '0');
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byteReceived := (others => '0');
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elsif rising_edge(baudClk) then
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waitBestPoint := 0;
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--getPoint <= '0';
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elsif rising_edge(baudOverSampleClk) then
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case current_s is
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case current_s is
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when bit0 =>
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when bit0 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(0) := serial_in;
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byteReceived(0) := serial_in;
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current_s <= bit1;
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current_s <= bit1;
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--getPoint <= '1';
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end if;
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when bit1 =>
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when bit1 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(1) := serial_in;
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byteReceived(1) := serial_in;
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current_s <= bit2;
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current_s <= bit2;
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--getPoint <= '1';
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end if;
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when bit2 =>
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when bit2 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(2) := serial_in;
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byteReceived(2) := serial_in;
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current_s <= bit3;
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current_s <= bit3;
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--getPoint <= '1';
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end if;
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when bit3 =>
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when bit3 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(3) := serial_in;
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byteReceived(3) := serial_in;
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current_s <= bit4;
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current_s <= bit4;
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--getPoint <= '1';
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end if;
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when bit4 =>
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when bit4 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(4) := serial_in;
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byteReceived(4) := serial_in;
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current_s <= bit5;
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current_s <= bit5;
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--getPoint <= '1';
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end if;
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when bit5 =>
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when bit5 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(5) := serial_in;
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byteReceived(5) := serial_in;
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current_s <= bit6;
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current_s <= bit6;
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--getPoint <= '1';
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end if;
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when bit6 =>
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when bit6 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(6) := serial_in;
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byteReceived(6) := serial_in;
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current_s <= bit7;
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current_s <= bit7;
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--getPoint <= '1';
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end if;
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when bit7 =>
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when bit7 =>
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data_ready <= '0';
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data_ready <= '0';
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if (waitBestPoint < numTicks) then
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waitBestPoint := waitBestPoint + 1;
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--getPoint <= '0';
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else
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waitBestPoint := 0;
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byteReceived(7) := serial_in;
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byteReceived(7) := serial_in;
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data_byte <= byteReceived;
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data_byte <= byteReceived;
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current_s <= rx_stop;
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current_s <= rx_stop;
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--getPoint <= '1';
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end if;
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when rx_stop =>
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when rx_stop =>
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data_ready <= '1';
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data_ready <= '1';
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data_byte <= byteReceived;
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data_byte <= byteReceived;
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current_s <= rx_idle;
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current_s <= rx_idle;
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